1. Field of the Invention
This invention relates to new and useful inventions in gripping devices and more particularly to adjustable wrenches.
2. Brief Description of the Prior Art
A number of types of adjustable wrenches are known in the prior art. Adjustable wrenches having a pair of adjustable jaws are available commercially. One simple type of adjustable wrench is known as the monkey wrench. Another adjustable wrench is the pipe wrench which has an adjustable jaw and a pivotal arrangement whereby the action of the handle in tightening and turning also tends to clamp the jaws tighter together. Adjustable clamping devices which fit around an object from a variety of directions are known in the case of drill chucks and lathe chucks. The patent literature reports some examples of attempts to produce adjustable socket wrenches. None of these, however, have achieved any commercial acceptance.
Koziel U.S. Pat. No. 1,768,988 discloses a socket wrench which is adaptable to use with nuts of varying diameters. This wrench has an adjustable lug or lugs which require independent adjustment. Lugs are also difficult to install and provide a gripping action on only two sides of the nut being turned by the wrench.
Lafin U.S. Pat. No. 1,501,788 discloses a socket wrench having a pair of fixed jaws and an adjustably moveable jaw. The adjustment arrangement is handled by clamping bolts and nuts. This wrench would tend to loosen with use rather than to tighten.
Johnson U.S. Pat. No. 2,381,597 discloses an adjustable socket wrench which is specially designed for applying and removing nuts having slots for engagement with the wrench. The device functions somewhat similarly to screw driver rather than a wrench.
Leibowitz U.S. Pat. No. 2,764,050 discloses an adjustable socket wrench having three clamping arms operated by a rotary cam which engages the moveable arms and pivots the same into engagement with the nut being clamped. The cam arrangement, however, is such that it tends to twist the clamping arm about its pivot point during the clamping operation.
Rockwell U.S. Pat. No. 3,972,253 discloses a multi-size socket wrench. This socket wrench has a fixed plate and a pair of adjustable jaws which are moveable against the nut or bolt head being clamped by the wrench. The jaws do not provide for a uniform clamping on the nut or bolt head with the clamping force being uniformly increased with rotation of the wrench.